Renal water excretion before and after remission of nephrotic syndrome: relationship between free water clearance and kidney function, arginine vasopressin, angiotensin II and aldosterone in plasma before and after oral water loading.

An oral water load of 20 ml/kg body wt. was given to eight patients with nephrotic syndrome before and after remission of the syndrome, and to 13 healthy control subjects. Urine volume (D), free water clearance (C water), plasma concentrations of arginine vasopressin (AVP), angiotensin II (ANG II) and aldosterone (Aldo), were determined before and three times during the first 4 h after loading. D and C water increased to a significantly lower level (P less than 0.01) after water loading in patients with nephrotic syndrome than in control subjects, but D and C water were normal after remission of the syndrome. The maximum increase in C water (delta C water max.) was 1.07 ml/min (median) before remission and 7.93 ml/min after, compared with 8.01 ml/min in the control group. Creatinine clearance (Ccr) increased significantly after remission (63 ml/min to 88 ml/min, P less than 0.01), and the fractional excretion of sodium was enhanced. AVP was higher in the nephrotic syndrome both before (2.9 pmol/l) and after remission (2.9 pmol/l) compared with the control group (1.8 pmol/l). ANG II and Aldo did not change after remission and remained at the same level as in the control group. The elevation in delta C water max. after remission was accompanied by an increase in Ccr in all patients and delta C water max. and Ccr were significantly correlated (rho = 0.600, n = 16, P less than 0.05). No relationship was found between the change in delta C water max. and ANG II and Aldo.(ABSTRACT TRUNCATED AT 250 WORDS)